Hydraulic pump assembly



Jan 3 1950 R. AMsLER 2,493,280

HYDRAULIC PUMP ASSEMBLY Filed Feb. 27, 1948 2 Sheets-Sheet 1 24 Figd 30 Figl 17 2416 Jan. 3, 1950 R. AMsLl-:R

HYDRAULIC PUMP ASSEMBLY Filed Feb. 27, 1948 IIIIIIIIIIIIIIIIII Patented Jan. 3, 1950 HYDRAULIQ PUMP ASSEMBLY Rudolf A msler, Neuhausen am Rheinfall, Switzerland, assigner to Schweizerische Industrie-- Gesellschaft, Neuhausen am Rheinfall, Switzery land, a Swiss firm Application February 27, 1948, Serial No. 11,769

In Switzerland February 5, 1947 Section 1, Public Law590, August 8, 1946 6 Claims.

The invention relates to improvements in hydraulically,ioperated pump assemblies for the delivery of a continuously adjustable quantity of liquid which, for instance, is required for the operation of feeding devices in machine tools.

It is an object of the invention to make the operation of the pump assembly independent of the condition and the temperature of the liquid, for instance oil, to be delivered.

Another object of the invention is a pump assembly which is adapted to operate against an adjustable pressure of the liquid to be delivered. the pressure of which may be higher or lower or which may be the same as the pressure of the operating liquid.

Thepump unit proper-at least one is provided and the same extends parallel to and is radially spaced from the axis of a rotatable operating plston-constitutes a reciprocatory hydraulic motor coupled with a pump. During the operation of the pump assembly the hydraulic motor and pump alternate their functions, that is, during movement in one direction the left side of the unit operates as a motor and the right side operates as a pump, while during the movement in the opposite direction the functions of the sides of the unit are reversed.

Still another object of the invention is to vary the amount of the delivery of the liquid by changing the stroke of the piston of the pump unit by I inserting a pin into the housing, one for each pump unit so as to limit the reciprocatory movement of the piston of the same. There will be providedas many pins as there are pump units in the assembly.

Another object of the invention is tov operate the pump unit, or pump units as the case may be, by an operating medium which is furnished by another pump which latter is arranged in the before mentioned rotatable operating piston. The latter is rotatably mounted in a casing in the wall of which are arranged longitudinal bores, one for each pump unit, each bore forming a cylinder for one of said pump units.

It is also an object of the invention to improve the volumetric efllciency of the pump assembly by operating both the drive end and the delivery end of the pump assembly withy the same pressure.

Other objects of the invention will be apparent or will be specifically pointed out in the description forming a part of this specification, but it is to be understood that the invention is not limited to the embodiments described in this description, as various forms may be adopted within the scope of the claims. l

Referring to the drawing:

Fig. 1 is a longitudinal sectional view of a pump assembly in accordance with the invention,

Fig. 2 is another longitudinal sectional view of the pump assembly substantially along the angular line C-C of Fig. 4,

Fig. 3 is a cross sectional view of the pump sembly substantially along the line A-A of Fig. 4 is a cross sectional view of the pump assembly along the line B--B of Fig. 2,

Fig. 5 is a longitudinal cross sectional view of a modification of a pump assembly according to the present invention,

Fig. 6 is a similar longitudinal cross sectional view as shown in Fig. 5, except that; the rotary piston is in another position and that the pistons of the pump unit have been shifted to another position, and

Figure 7 is a cross sectional view of the pump assembly substantially along the line D-D of Fig. 5.

Referring to the drawings, particularly Fig. 1, the pump assembly consists of three principal parts, namely the drive shaft A with the operating piston I thereon, the cylindrical casing B and the adjusting device C. The operating piston I and the shaft A rotate as a unit and are driven by a motor, not shown. Within the operating piston I is arranged a pump 2 which in the embodiment shown comprises a screw pump consisting of a center screw 2EL and two lateral screws 3l which have a smaller diameter than the center screw 2a. The two screws 31 are rotatably supported in the operating piston I and when the latter is rotated the two lateral screws 31 are caused to roll about the center screw 2a, since the thread of the screws 3l engages the thread of the screw 2a. The center screw 2a is provided with an outwardly projecting threaded portion 2b which projects through the cover 36 of the casing B and has attached thereto a nut which secures the center screw 2a xedly to the cover 36. When the operating piston I is rotated in the manner described, the operating fluid entering the ports or slots 3 at one end of the casing B travels along the center screw 2a and is forced into the chamber 4 at the other endof the casing B. A conduit 5 connects the chamber 4 with the device to be operated by the liquid.

The operating piston I is also provided with two longitudinal passages 6 and 'I which extend parallel to the axis of the screw 2a and are continuously in communication with the chamber Il. In the position of the operating piston I as shown in Fig. 1 the operating iluid is conducted by the passage 6 and the ports 8 and 9 into the right end of the cylinder I formed by a portion of a longitudinal bore arranged in the wall of the casing and extending parallel to the axis of the operating piston I. The left end of the cylinder I0 is in communication with the port I I, the passage I2, the annular passage I3 and the port I4 which latter discharges the liquid from the pump assembly. Furthermore, the passage 6 by means of the ports I and I6 conducts operating liquid to the right end of the cylinder I1 'which is formed by another portion of the cylindrical bore arranged in the wall of the casing B. The left end of the cylinder I1 is connected by the port I8, the passage I9 and the annular passage with a conduit 2I which conducts the operating liquid to the devices to be operated. The longitudinal bore forming the axially alined cylinders I and I1 has mounted therein three axially aligned but separated pistons 22, 23 and 24 all of which move toward the left so that the operating liquid in the left end of the cylinder I1 is forced toward the device to be operated. This movement of the pistons 22, 23 and 24 takes place by the operating liquid entering the right end of the cylinder I0. The piston 22 in this instance functions as motor piston while the piston 24 in the cylinder I1 functions as pump piston.

Upon rotation of the operating piston I about an angle of 180, which position is illustrated in Fig. 2, the just described operation of the pump unit is reversed. The operating liquid is now conducted by the passage 1 into the ports 25 and I8 and into the left side of the cylinder I1 and the piston 24 therein acts as motor piston and moves the other pistons 23 and 22 toward the right. The right end of the cylinder I1 by means of the port I6, the passage 26 and the annular passage I3 is connected with the discharge port I4. Furthermore, the passage 1 conducts operating liquid by means ,of the ports 26 and II into the left end of the cylinder IIJ; and into the right end of the cylinder I0 by means of the port 9, the passage 21, the annular passage 28 and the passage 29 is connected with the line 2I which conducts the operating liquid to the device to be operated. The pistons 22, 23 and 24 move toward the right and the operating liquid in the right end of the cylinder I0 is thereby forced into passages 9, 21, 28, 29 and 2| which lead to the device to be operated.

The adjustment of the quantity of liquid to be delivered is affected by the longitudinally slidable pin 30 which extends into the outer end of the bore forming the cylinders I0 and I1. A manually rotatable hand Wheel 3I is in threaded engagement with the outer end 2b of the central screw 2i and has an annular flange which engages the outer end of the pin 30 as shown in Figs. 1 and 2. In case that the pump assembly is provided with a plurality of pump units I0, I1, 22, 23 and 24 there are provided a corresponding number of pins 30, but all of these pins are simultaneously adjusted by a single hand wheel 3|. If desired, the manually operable adjusting device may also be hydraulically adjusted.

In order to assure that the pressure of the operating liquid will be the same as the pressure of the delivered liquid, that is, the liquid which is conducted to the devices to be operated, it is advisable to conduct the liquid delivered by the pump unit or units, for instance the liquid in the line 2|, to the right side of an equalizer or '4 adjusting piston l2 as shown in Fig. 1. From the right side of the chamber in which the piston 32 is slidably mounted, a line 33 leads to the devices to be operated. The left side of the chamber in which the piston 32 is arranged is in communication with the pressure chamber 4 in the casing B. The arrangement is such that the piston 32 is automatically adjusted to such a position that the pressure in the line 5 will be the same as the pressure in the line 33. 34 is a stopl which limits the movement of the piston 22 toward the right and 35 designates the other cover of the cylindrical casing B.

If the pump assembly has to deliver another medium other than that of the operating medium, a condition which, for instance, may arise in the chemical industry, then this condition can easily be met by the pump assembly of the present invention. It is only necessary to connect the outer ends of the cylinders I0 and I1, which in the above identied embodiment are brought into communication with the devices to be operated by the liquid, in communication with the discharge ports. Fig. 5 illustrates by way of example in a longitudinal sectional view such a modified pump assembly and Fig. 6 illustrates in a partial sectional view this modification after the operating piston has-been rotated about an angle of from its position shown in Fig. 5. The passage I4, which by means of the annular passage I3, the passages I2 and 26 and the ports II and I6 is connected with the inner ends of the cylinders I0 and I1 leads to the devices to be operated. The liquid is admitted to the cylinders I0 and I1 by means of the ports II, I6, 4B and 4I, the passage 42, the annular passage 43 and the supply conduit 44. The operation of the pump assembly is the same as already described.

What I claim as my invention is:

1. A hydraulic Ipump 'assembly comprising a casing closed at both ends and having mounted therein a rotatable operating piston, pump means within said operating Ipiston and operable upon rotation of said operating piston to convey liquid from an inlet lat one end of said casing to an outlet atthe other end of said casing, the wall of said casing having a bore therein extending parallel to the axis of rotation of said operating piston and means at opposite ends of said casing wall forming a supply port and -a delivery conduit respectively, a discharge conduit between the ends of said casing, and a .piston assembly consisting of at least three axially alined separate parts mounted for reci-procative movement in said bore, said operating piston and said casing being each provided with passages and ports adapted to connect said other end of thecasing with said ybore in a manner that said separate parts of the piston assembly, upon rotation of said operating piston, are actuated to function alternately as Ipump -piston and motor piston to deliver Iand expel fluid into said delivery conduit and discharge conduit respectively.

2. A hydraulic pump assembly comprising a casing closed at .bothv ends and having mounted therein a rotatable operating piston, pump means within said operating piston and operable upon rotation of said operating piston to convey an operating liquid from an inlet at one end of said casing to an outlet at the vother end of said casing, the Wa-ll of said casing having a bore therein extending parallel to the axis of rotation of said operating piston and means at opposite ends of said casing wall forming a supply port and a delivery conduit respectively. a discharge conduit amano between the ends of said casing, and a piston assembly consisting of at least three axially alined separate parts mounted for reciprocative movement in said bore, said operating piston and said casing being each provided with passages and ports adapted to connect said supply port, delivery conduit and discharge conduit with said bore in a manner that said separate parts of the piston assembly, upon rotation of said operating piston, are actuated to function alternately as pump piston and motor :piston to deliver and expel another fluid into said delivery conduit and discharge conduit respectively.

3. A hydraulic pump assembly comprising a casing closed at both ends and having mounted therein a rotatable operating piston, pump means within said operating piston and operable upon rotation of said operating piston to convey liquid from an inlet at one end oi' said casing to an outlet at the other end of said casing, the wall of said casing having a bore therein extending parallel to the axis of rotation of said operating piston and means at opposite ends of said casing wall forming a supply port and a delivery conduit respectively. a discharge conduit between the ends of said casing, a piston assembly consisting of at least three axially alined separate parts mounted for reoiprocative movement in said bore, said operating piston and said casing being each provided with passages and ports adapted to connect said other end of the casing with said bore in a manner that said separate parts of the piston assembly, upon rotation of said operating piston, are actuated to function alternately as pump .piston and motor piston to deliver and expel iiuid into said delivery conduit and discharge conduit respectively, and pressure regulating means Ifor automatically equalizing the pressure of the liquid in said other end of the casing and in said delivery conduit.

4. A hydraulic pump as claimed in claim 1, in which the pump means in said operating piston consists of a screw pump the main axis of which is coincident with the axis of rotation of said operating piston.

5. A hydraulic pump assembly comprising a casing closed at both ends and having mounted therein a rotatable operating piston, pump means within said operating -piston and operable upon rotation of said operating piston to convey liquid from an inlet at one end of said casing to a-n 6 outlet at the other end of said casing, the wall oi said casing having a bore therein extending parallel to the axis of rotation of said .operating piston and means at opposite ends of said casing wall forming a supply port and a delivery conduit respectively, a discharge conduit between the ends of said casing, a piston assembly consisting of at least three axially alined separate parts mounted for reciprocative movement in said bore, said operating piston and said casing being each provided with passages and ports adapted to connect said other end of the casing with said bore in a manner that said separate parts oi' the piston assembly, upon rotation of said operating piston, are actuated to function alternately as pump lpiston and motor piston to deliver and expel iluid into said delivery conduit and discharge conduit respectively, and means for gradually varying the stroke of the reciprocating piston assembly.

6. A hydraulic pump assembly comprising a casing closed at both ends and having mounted therein a rotatable operating piston, pump means within said operating piston and operable upon rotation of said operating piston to convey liquid from an inlet at one end of said casing to an outlet at the other end of said casing, the wall of said casing having a bore therein extending parallel to the axis of rotation of said operating piston and means at opposite ends of said casing wall forming a supply port and a delivery conduit respectively, a discharge conduit between the ends of said casing, a piston assembly consisting of at least three axially alined separate parts mounted for reeiprocative movement in said bore, said operating piston and said casing 'being each provided with passages and ports adapted to connect said other end of the casing with said Ibore in a manner that said separate parts of the piston assembly, upon rotation of said operating piston, are actuated to function alternately as pump piston and motor piston to deliver and expel duid into said delivery conduit and discharge conduit respectively, and manually operable adjusting means attached to the outside of said casing and adapted to engage one end of said reciprocating piston assembly to vary the stroke of the same, whereby the delivery of the amount of liquid is varied.

RUDOLF AMSLER.

No references cited. 

